1. Field of the Invention
This invention generally relates to semiconductor manufacturing equipment and, more particularly, to an apparatus and method used for the processing of semiconductor wafers.
2. Description of the Related Art
In the semiconductor industry, advancements in the development of semiconductor devices of decreased dimensions require the development of new processing and manufacturing techniques. One such processing technique is known as Rapid Thermal Processing (RTP). The RTP technique reduces the amount of time that a semiconductor device is exposed to high temperatures during processing. The RTP technique, typically includes irradiating the semiconductor device or wafer with sufficient power to rapidly raise the temperature of the wafer and maintaining the temperature for a time period long enough to successfully perform a fabrication process, but which avoids such problems as unwanted dopant diffusion that would otherwise occur during longer exposure to high processing temperatures.
Generally, conventional RTP systems use a radiation source and reflectors to heat the bulk of the semiconductor wafer. The radiation source is usually a bank of lamps that emit radiation energy that is focused on the wafer by the reflectors.
Conventional lamp-based RTP systems have considerable drawbacks with regard to achieving and maintaining a uniform temperature distribution across the active layer of the wafer surface. By applying more power to the filament, the power intensity of the lamp may be increased. However, the power density of direct radiation is limited by the rating of lamps and further by packing density of the lamps.
Temperature fluctuations occur on the surface of the wafer which may cause crystal defects and slip dislocations in the wafer at high temperatures (e.g. ˜1000 ° C). Further, the heating ramp rate and maximum temperature achievable are limited by the power density of the lamps.
For the above reasons, what is needed is an apparatus and method for uniformly and controllably heating the surface of a semiconductor wafer during rapid thermal processing.